Fish in marinade with vinegar - how long?

Every week, SO and I usually enjoy a nice seared tuna with scallops. It seems that the texture of the finished product varies somewhat each week and sometimes feels tough as if it's been denatured too much prior to searing (quick 45-1 minute each side). My marinade usually includes garlic, ginger, soy sauce, rice wine vinegar and I only marinate for 10-15 minutes on each side for both the scallops and the tuna. I'm not really looking for a new marinade as we love this mixture but of the ingredients it seems to me that the likely offenders might be the ginger or vinegar. Any other ideas? Should I just add them after it marinates as we use the remaining liquid as a sauce?

I have no clue we have made the same dish for years now and have always marinated it. I think actually once we didn't and simply sprinkled pepper and served with the sauce and didn't find it to be the same and prefer the marinade method. I guess it must have some effect?

Leave the vinegar out of your marinade and replace it with an equal amount of neutral tasting oil. Proceed with the recipe, and compare with the original. The flavor of the soy, garlic and ginger should be stronger.

It seems like you are making something very close to a teriyaki sauce, but using a different technique. Traditional teriyaki adds the sauce midway through the cooking to produce a glaze. Ginger is added to reduce the fishiness. The real difference is teriyaki uses mirin and sake instead of vinegar.

I recommend that you learn to make your own teriyaki sauce. it keeps indefinitely and is far better than what you can buy. If you learn to cook with it you will get a better result than marinating with vinegar.

I'm actually not really a fan of teriyaki and given that this recipe has pretty low sugar which I think is a prominent feature of teriyaki or at least the versions I've had it doesn't really taste like any teriyaki that I've ever eaten. I am not averse to learning to make teriyaki sauce and have done so in the past and not against it as a separate dish, but the post was not intended to say we don't like our current prep and to ask for different ingredients. We highly enjoy this dish and I was asking more so if there is a different way to incorporate the ingredients that we currently use to alter the texture of the meat slightly.

I think perhaps the best at least thing to try before moving on is to add the vinegar afterwards.

I'd suggest 15 minutes marinating in all the ingredients except the rice vinegar. Add it a couple of minutes before searing, but no more. The texture of the fish and scallops should remain intact this way.